I am funny-style, and cheap. Not only that, my bikes don't even cost that much. With that said, I use a home-depot $5.99 combination-cable lock. The trick is, the bikes are NEVER out of my sight!! When I commute to work, I stop and eat breakfast at a Panera Bread. There is a railing about 5 yards from my table. I lock my bike with the cable lock, but I got eyeball on it all the time. When I get to work (at a college), I take my bike inside with me and it sets in a locked storeroom right next to my cube.

I am never going to lock up my bike and let it be out of sight, even my cheapos.. .. I had one bike stolen, it was locked, and I was lucky to have it recovered. When I have to go into a store, the bike comes with me..Like I said, I am funny-style and parinoid..